Thermal retarder unit



Feb. 11, 1947;

c. M. OSTERHELD 2,415,523

THERMAL RETARDER UNIT Filed Sept. 20, 1944 2 Sheets-Sheet l IN V EN TOR. 62 AM 057mm D ATTORNE Y Feb. 11, 1947. c OSTERHELD 2,415,523

THERMAL RETARDER UNIT I Filed Sept. 20, 1944 2 Sheets-Sheet 2 l a7 67 .9/ 73 65 i 2 as 3 1 5.9 I a 6/ s: 1 l I 1: 5 377 97 IN V EN TOR.

A TTORNEY Patented Feb. 11, 1947 THERMAL RETARDER UNIT Clark M. Osterheld, Stoughton, Wis., assignor to McGraw Electric Company, Elgin, 111., a corporation of Delaware Application September 20, 1944, Serial No. 555,001

10 Claims.

My invention relates to electric heater control devices and particularly to thermal retarder heater control switch units.

An object of my invention is to provide a relatively simple, inexpensive, and easily manufactured thermal retarder heater control switch unit to selectively cause immediate energization of the electric heater of a domestic hot water tank or energization of the heater with a predetermined time period of delay in accordance with the amount of cold water in the tank at the start of an oil-peak period.

Other objects of my invention will either appear in the course of a description of a device embodying my invention, or will be pointed out in the course of such description and set forth in the appended claims.

In the drawings,

Figure 1 is a vertical, sectional view of a domestic hot water tank, having associated therewith a device embodying my invention,

Fig. 2 is a diagram of connections used with the device embodying my invention, showing the contacts in the position when the tank is either entirely full of cold water or is more than half full of cold water,

Fig. 3 is a diagram of connections similar to Fig. 2, except that the contacts are shown in the positions occupied by them when the tank is more than half full of hot water,

Fig. 4 is a diagram of circuits, showing a different method of control of the heating coil for the thermal retarder,

Fig. 5 is a diagram of connections, showing a circuit of a different kind for the thermal retarder heating coil,

Fig. 6 is a top plan view of a thermal retarder unit shown in Fig. '7,

Fig. 7 is a vertical, sectional view of the thermal retarder unit taken on the line of Figs. 6 and 8, and,

Fig. 8 is a front view of the device shown in Figs. 6 and '7, with the cover shown in section.

Referring first of all to Fig. 1 of the drawings, I have there shown an ordinary domestic hot Water tank having a lower cold water inlet pipe l3, an upper hot water outlet pipe l5, a mass i? of heat insulation around the tank H, which heat insulation is held in proper operative position around the tank by an outer casing I9, I provide also, preferably, but not necessarily, a single electric heater 2|. which is shown as of the clamp-0n type secured around the outside of the tank; and if only a singl heater is used, it

tion of the tank The heater 2| may be located in a tunnel member 23, and I wish to here point out that all of the above detailed elements are old and well known in the art and constitute no part of my present invention.

I provide a lower thermally-actuable heater control switch, designated by numeral 25, and I have shown this switch as comprising a bimetal bar 21, having one end mounted on a contact 29, While the other end thereof is adapted to move into and out of engagement with a second fixed contact 3|. The two contacts 3| and 29 and the bimetal bar 2! are adapted to be mounted on the outside of the tank in heat-receiving relation thereto. While I have shown a specific embodiment of a thermally-actuable switch, I do not desire to be limited thereto, since any other form of thermally-actuable switch, operative in the same manner and for the same purpose as the switch 25, may be used instead. The design, construction, and operation of the lower thermallyactuable heater control switch 25 is such that when the lower end portion of the tank is filled with cold water, the bimetal bar 21 will be in engagement with fixed contact 3|, while if the lower end portion of the tank contains hot water, it will be out of engagement therewith. When I speak of cold water. I refer to water the temperature of which is on the order of F. to F.; while when I speak of hot water, I refer to water the temperature of which is on th order of F., or slightly over.

I provide a thermal retarder heater control switch unit 33, which is shown in several views in Figs. 6, 7, and 8. I provide a supporting block 35, the inner face of which is of arcuate shape, so that its entire inner surface will be in close heat-receiving relation to and in engagement with the outside surface of the tank I I, and member 35 may be held in proper operative positions as by welding seams 31. The outer surface of supporting block 35 may be of substantially flat planar shape, and a base member 39 of heatconducting material may be secured against the outer surface of block 35 as by a plurality of machine screws 4| and 43. Member 39 has integral therewith a projecting part 45, the central outer face of which is of substantially a'rcuate shape and which has extending axially thereof a here or recess 41. In the bore or recess 41, I locate an expansion chamber or bellows 49, the lower end of which is connected to a plate 5|, which has centrally thereof and extending axially thereof a tubular extension 53. The upper is to be located adjacent to the bottom end por- 55 end of the bellows 49 has secured thereto a substantially circular plate 55, the joint between the lower member 5| and the bellows 49 and between the upper member 55 and the bellows 39 being fluid and gas tight, and I fill the closed exp bellows with a suitable volatilizable material well known in the art, which will operate in the desired manner to be hereinafter set forth.

The upper closure plate 55 has mounted thereon an upwardly-extending rod 51, which has positioned thereon intermediate its ends a block 59 of electric-insulating material, which is held in proper operative position on rod 51 by a pin 6! extending partly through block 59 and through rod 51.

Member 45 is provided with two integral, horizontally-extending side portions E3, which are adapted to support a block 65 of electric-insulating material, which is of substantially inverted U-shape and which has on its upper surface a projecting central portion 61. Member 65 may be held on the side portion 63 by short machine screws 69.

A plurality of contact members are supported on block 65 in spaced relation relatively to each other. These fixed contacts comprise two main central contacts H and I3 which are each of substantially U-shape, as may be seen in Fig. 7, and which are secured to electric-conducting terminal members I5 and I! of L-shape, secured to the front surface of block 65 as by screws I9.

lock 59 has mounted thereon and extending forwardly therefrom a contact bridging member 8|, which is adapted to engage the contacts ii and '53, either at the lower leg portion or at the upper leg portion, in accordance with the vertical position of rod 5'! and block 59 and as moved thereinto by the expanding and contracting bellows so. The projection 61 on block has mounted thereon a guide bar 83 secured thereto by a screw 85, the inner end of bar 83 overhanging and surrounding the rod 51 and being provided with an opening therein, coaxially aligned with rod 51, in which opening there is mounted a hollow adjusting member 81, having screwthreaded engagement with member 83 and being adapted to be held in adjusted position by a lock nut 89. A small spring BI is positioned in the tubular member 8?, so as to provide an opposing spring pressure of predetermined value against upward movement of rod 51.

I provide further two fixed contact terminals 93 and 95 adjacent-to the ends of block $5, contact member '95 having secured thereto an inwardly-extending metal bar 9?, which has mounted thereon a contact 99 adapted to be engaged with a depending contact IilI on contact 13. Block 59 has a shoulder portion its at its lower face, which shoulder portion is adapted to be engaged by bar 9?, so that when the length of the bellows or the expansion chamber 48 is a minimum, the contacts as and IE]! will be out of engagement with each other, but upon temperature rise of the bellows 49 an increase of its over all length will cause engagement of the two con tact 59 and I ill, the bar 91 being biased normally upwardly, so as to hold the two contacts as and iol in engagement with each other when permitted to do so by upward movement or'block 5e.

Tubular member 53 has positioned therein a small heating coil W5, which may be mounted on an insulating support I 01. The amount of energy translated into heat in heating coil I 35 is relatively small, so that the desired maximum temperature to which it can heat the material in the expansion chamber will not be. reached in less iii) than say four hours after starting energization. Two conductors Hi9 and III connect the terminals of heating coil I05 to contact terminals 93 and I provide a cover H3 for the thermal retarder and provide further a lower plate I IE to complete the enclosure of the thermal retarder unit, this bottom plate H5 being held by screws ill.

Referring now to Fig. 2 of the drawings, I have tlshown a diagram of connections used with thv thermal retarder hown in Figs. 6, '7, and 8.

I provide a time-controlled switch l2 comprising a first contact arm I23 and a second contact arm which contact arms are adapted to be out of engagement with each other during on-peak periods of a twenty-four hour day to be held in engagement with each other during all off-peak periods of a twenty-four hour day by a continuously operating timing mechaof any well known kind now used in the art. I provide two supply circuit conductors I21 and 52E of which conductor I2? is electrically connected with contact arm I23. Contact arm I25 is connected by a conductor It! to the two contacts ii. The contacts "F3 are connected by a conductor I33 with one terminal of the electric heater 25, the other terminal of which is connected a conductor :35 with fixed contact 3|. Klontact is connected by a conductor Hill to the supply circuit conductor I29. The one terminal of heating coil I05, connected with the i contact 95, is connected to the resilient contact arm or by conductor I l I, as has already been hereinbefore set forth, while the other terminal of heating coil 1&5 is connected by a conductor with contact 3!.

Let it now be assumed that the tank is more than half full of cold water, so that the thermal retarder unit will be subject to cold water, with the result that contact bridging member 8i will bein engagement with the lower of the two contacts l! and I3, a shown in Fig. 2 of the drawings. If this condition obtains during on-peak time, the heater circuit will not be energized, because of the fact that the two contact arms I23 and E25 of the time-controlled switch are out of engagement with each other, but since the switch is closed at the start of an cit-peak period, which for illustrative purposes may be considered to start at 10 p. m. or 11 p. m., the following circuit will be energized: from supply circuit conductor 52? through closed switch IZi, conductor I3l, contact members ll, bridging member [H to one of the contacts it, through conductor I33, electric heater 2!, conductor H5, through closed switch and through conductor 37 to the second supply circuit conductor 129. Thus, if the tank is either completely filled with cold water, or more half full of cold water, energization of heater will occur immediately after closing of the time-controlled switch at the start of an oil-peak period. I

This energization of heater 2! will continue until enough additional water has been heated to a temperature on the order of F. to subject the thermal retarder switch unit to hot water. The hereinbefore mentioned spring QI, opposing upward movement of rod 57, helps in preventing disengagement of bridging member 8! from the lower contacts II and 73, in accordance with the relatively large change and increase of temperature of the expansion bellows, which, as was hereinbefore set forth, is in good heat-conducting relation with the water in the tank; and I may here point out that, preferably, the thermal retarder unit is positioned at substantially the halfheight of the tank, although I do not desire to be limited to this one position.

When the thermal retarder switch unit is subject to hot water, contact bridging member 8| will be moved into the position shown in Fig. 3 of the drawings, with the result that energization of heater 2| is interrupted. An energizing circuit is, however, closed through the heating coil I05, this circuit being traceable as follows: from supply circuit conductor I21, through closed switch I2I, conductor I3I, to the two contacts 1|, from and through resilient arm 91, conductor I I I, heating coil I 05, conductor I39, and through closed switch and conductor I31, to the second supply circuit conductor I29. The energization of heating coil I05 will result in increasing the temperature of the expansion chamber in a predetermined time, which may be on the order of four hours, or even less, so that at the end of the predetermined time, a temperature on the order of 250 F. will have been reached, with the result that bridging member BI is moved into engagement with the upper contacts 1| and 13, whereby reenergization of the heater 2| is effected.

This energization of heater 2| will continue until either substantially all of the water in the tank is hot, when the lower thermally-actuable switch 25 will deenergize heater 2|, if this happens before the end of an off-peak period. If, however, for any reason, less than all of the water in the tank is hot at the end of an off-peak period, switch 25 will still be in closed position and deenergization of heater 2| will be effected by the time-controlled switch |2| at the end of an offpeak period.

Referring now to Fig. 4 of the drawings, I have there shown a modified form of control for the heating coil I05. In this diagram I provide an electromagnetic relay I40, comprising a pair of fixed contacts MI and I43, which are adapted to be engaged by and be disengaged from a bridging member I45, which is connected with a magnetizable armature core I41, adapted to be energized by a coil I49. One terminal of coil I49 is connected by a conductor |5| to one terminal of heater 2| and by a second conductor I53 to the upper contact 13. In this diagram, the lower contact, which was numbered 13 in Figs. 2 and 3, is not now connected with the upper contact; and I have therefore designated it as contact I55. Contact I55 is connected by a conductor I51 to the other terminal of coil I49. The other terminal of heating coil I05 is connected by a conductor I59 to the two contacts 1|.

When the time-controlled switch is closed at the start of an off-peak period, and assuming that the thermal retarder unit is subject to cold water, with engagement of the bridging member 8| with the lower contact 1| and contact I55, the following energizing circuit through heater 2| will be established: from the first supply circuit conductor I21, through closed switch I2I, through conductor |3I to cont-acts 1|, contact bridging member 8|, contact I55, conductor I51, coil I49, conductor I5I, heater 2|, conductor I 35, closed switch 25, and through conductor I31 to the second supply circuit conductor I29- The other terminal of heating coil I05 is connected to fixed terminal I43 by a conductor I6 I, while contact MI is connected by a conductor I63 with fixed contact 3|. The energized coil I49, traversed by the current traversing heater 2|, causes upward movement of the core I41 and of the bridging member I45, whereby the energizing circuit of heating coil I05, traceable as follows, is interrupted: from supply circuit conductor I21, through closed switch I 2|, conductor I3I, contacts 1|, conductor I59, heatin coil I05, conductor I6I, through contacts I43 and MI with bridging member I45, conductor I83, closed switch 25, and through conductor I31 to the second supply circuit conductor I29. This circuit is, of course, established when coil I49 carries no current.

Energization of heater 2| will continue until enough water has been heated to subject the thermal retarder unit to hot water, when contact bridging member 8| will be moved upwardly out of engagement with the fixed contacts 1| and I55, whereby energization of coil I49 will be interrupted. When this happens, contact bridging member I45 will drop downwardly into engagement with the fixed contacts MI and I43, with the result that heating coil I05 is energized. Energized heating coil I05 causes temperature rise of the expansion chamber so that at the end of a predetermined period of time, say three or four hours, the temperature of the expansion chamber will be on the order of 250 F., with the result that contact bridging member 8| is moved into engagement with the upper contacts 1| and 13, whereby a new energizing circuit for heater 2| is established, traceable as follows: from supply circuit conductor I21 through closed switch I2I, conductor I3I, through the upper contacts H and 13, and engagin bridging member 8|, through conductors I53 and I5I, heater 2|, conductor I35, and through closed switch 25 and conductor I31 to the second supply circuit conductor I29.

Energization of heater 2| will continue until substantially all of the water in the tank is hot, at which time lower thermally-actuable switch 25 will deenergize heater 2|, if this condition occurs before opening of the time-controlled switch I2I If less than substantially all of the Water in the tank is hot at the end of an off-peak period for any reason whatever, energization of heater 2| will be interrupted by the time-controlled switch IZI.

Referring now to Fig, 5 of the drawings, I have there shown a slightly modified diagram of circuit connections which may b used. I provide an electromagnetic relay or contactor I61, which comprises a pair of fixed contacts I69 and HI adapted to be engaged by and disengaged from a contact bridging member I13, which is insulatedly supported by an armature core I15 adapted to be energized by a coil I11. A switch for controlling the energization of coil I11 is shown as a pivotally mounted contact arm I19 adapted to engage an upper contact member |8I and a lower contact member I03, being moved into these respective positions by the expansion chamber 49. Contact arm I25 of the time switch is connected by a conductor I with contact I8I, and a conductor I81 connects contacts I8I and I83 to each other. Resilient contact arm 91 is adapted to engage with and be disengaged from contact I83 and is connected by a conductor I89 with one terminal of heating coil I35, the other terminal of which is connected with contact 3| by a conductor I 39. One terminal of heating coil 2| is connected by a conductor I9I to fixed contact I1I, while contact I69 is connected by a conductor I93 to fixed contact I8I. One terminal of coil I11 is connected to conductor I31, while the other terminal is connected to contact arm I19.

Let it now be assumed that the time-controlled switch I2I has been moved to closed position'by the timer at the start of an off-peak period; and that contact arm I19 is in engagement with the lower contact I 83 by reason of the fact that thermal retarder switch unit is subject to cold water in the tank. Under these conditions energization of the heater 2| will occur through a circuit established by energization of coil I11 of the contactor I61 and engagement of bridging member I13 with contacts I69 and HI traceable as follows: from supply circuit conductor I21, through closed switch I2I, through conductor I95 to contact I8I, conductor it", through the engaged contacts I69 and HI with bridging member I13, through conductor I9I, heater 2I, conductor I35, closed switch 21, and through conductor I 31 to the second supply circuit conductor I29. This circuit has been established, as has already been hereinbefore stated, because of the energization of coil I11 through a circuit as follows: from supply circuit conductor I21, closed switch I2! con ductor I85, contact I 9|, conductor I81, contact I83, contact arm I19, coil I11, to the second supply circuit conductor I29.

This energization of heater 2! will continue for a length of time sufiicient to heat enough water in the tank to subject the thermal retarder unit to hot water, when contact arm I19 will be moved to the position shown in Fig. by broken lines, so that it is out of engagement with the two contacts I83 and NH. When this happens, contact arm 91 will move upwardly into engagement with contact I83, whereby an energizing circuit is closed through heating coil I05, traceable as follows: from supply circuit conductor I21, through closed switch I2I, conductor I85, contact I81, conductor I81, contact I83, contact arm 91, conductor I39, heating coil I05, conductor I39, closed switch 29, and through conductor I31 to the second supply circuit conductor I29.

The energization of heating coi1 I05 will cause temperature rise of the expansion chamber, with the result that in a period of time on the order of three or four hours, the temperature of expansion chamber 49 will have been raised to a value sufficient to cause the expansion chamber to move contact arm I19 into engagement with contact I8I, whereby coil I11 is energized, resulting in engagement of bridging member I13 with contacts I69 and HI and attendant energization of heater 2i through substantially the same circuit as hereinbefore set forth. This energization or heater 2i will continue until either substantially all of the water in the tank is hot and the eater is deenergized by switch 25, if this occurs before the end of an ofi-peak period; or if less than all of the water in the tank is hot at the end of an off-peak period, opening of the time-controlled switch will deenergize heater 2|.

The device embodying my invention is therefore effective to selectively energize an electric heater for a domestic hot water storage tank, either immediately at the start of an off-peak period, or after a predetermined time period of delay, in accordance with the amount of cold water in the tank at the start of an off-peak period.

Various modifications may be made in the device embodying my invention without departing from the spirit and scope thereof, and all such modifications comin clearly within the scope of the appended claims shall be considered as covered thereby. T

I claim as my invention:

l. A thermal retarder switch unit for hot wa ter storage tank heaters, comprising a thermoresponsive expansion chamber adapted to be mounted in heat-receiving relation with the water in a tank, switching means operable by said expansion chamber having two opposite closed positions and an intermediate open position and means independent of the tank for exchanging heat with the expansion chamber.

2. A thermal retarder switch unit for hot water storage tank heaters comprising a thermoresponsive expansion chamber adapted to be mounted in heat-receiving relation with the water in a tank, switching means operable by said expansion chamber having two opposite closed positions and an intermediate open position and means independent of the tank for raising the temperature of said expansion chamber.

. 3. A thermal retarder switch unit for hot-wag ter storage tank heaters comprising a thermoresponsive expansion chamber adapted to be mounted in heat-receiving relation with the water in a tank, switching means operable by said expansion chamber having two opposite closed positions and an intermediate open position and normally located in a first closed position and movable into open position and then into a second closed position in accordance with predetermined temperature increases of said expansion chamber.

4. A thermal retarder switch unit for hot water storage tank heaters, comprising a thermoresponsive expansion chamber adapted to be mounted in heat-receiving relation with the water in a tank, switchin means operable by said expansion chamber having two opposite closed positions and an intermediate open position and means independent of the tank for exchanging heat with the expansion chamber, said switching means being normally located in a first closed position when the expansion chamber is subject to cold water in the tank and movable into open position and then into a second closed position in accordance with predetermined temperature increase of said expansion chamber.

5. A thermal retarder switch unit for a hot water storage tank heater, comprising a thermoresponsive expansion chamber adapted to be mounted in heat-receiving relation with the water in a tank, switching means operable by said expansion chamber having two opposite closed positions and an intermediate open position and a heating coil for said expansion chamber, said switching means being held in a first closed position when said expansion chamber is subject to cold water in the tank, being moved in open position when said expansion chamber is subject to hot water in the tank and being moved into a second closed position with a predetermined time period of delay after energization of said heating coil.

6. A thermal retarder switch unit for hot water storage tank heaters comprising a thermo-responsive expansion chamber adapted to be mounted in heat-receiving relation with the Water in a tank, switching means operable by said expansion chamber having two opposite closed positions and an intermediate open position and a heating coil for said expansion chamber, the energization of which is controlled by said expansion chamber.

7. A thermal retarder switch unit for hot water storage tank heaters comprising a thermo-responsive expansion chamber adapted to be mounted in heat-receiving relation with the water in a tank, switching means operable by said expansion chamber 'having two opposite closed positions and an intermediate open position and a heating coil for said expansion chamber adapted to be deenergized with the expansion chamber is subject to cold water in the tank and to be energized when the expansion chamber is subject to hot water in the tank.

8. A thermal retarder switch unit for hot water storage tank heaters, comprising a thermo-responsive expansion chamber adapted to be mounted in heat-receiving relation with the water in a tank, switching means operable by said expansion chamber having two opposite closed positions and an intermediate open position, a heating coil for said expansion chamber and means controlled by said expansion chamber for causing deenergization of said heating coil when the expansion chamber is subject to cold water in the tank and for causing energization of said heating coil when the expansion chamber is subject to hot water in the tank.

9. A thermal retarder heater control switch unit for a hot water storage tank electric heater, comprising a single thermo-responsive expansion chamber adapted to be mounted in heat-receiving relation with the water in a tank intermediate the ends thereof and switching means controlled by said expansion chamber to prevent energization of said heater until after the elapse of a predetermined length of time after entry of a predetermined relatively small quantity of cold water into the tank.

10. A thermal retarder switch unit for a hot 10 water storage tank heater comprising a thermoresponsive expansion chamber, a heating coil for said expansion chamber, switching means actuable by said expansion chamber comprising two pairs of electrically connected fixed contact members, a contact bridging member and a contact arm movable by said expansion chamber, said contact bridging member being in engagement with two fixed contact members and said contact arm being out of engagement with one of said fixed contact members to cause energization of said heater when said expansion chamber is at a relatively low temperature, said contact bridging member being out of engagement with said fixed contact members and said contact arm being in engagement with said one fixed contact member when said expansion chamber is at an intermediate temperature and said contact bridging member being in engagement with the other two fixed contact members when the temperature of said expansion chamber is at a relatively high value.

CLARK M. OSTERHELD.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,073,286 Raney Mar. 9, 1937 2,304,103 Kelly Dec. 8, 1942 

